Search

Share:

The Internet site that you are about to view is an online educational resource intended
for medical professionals based in the United Kingdom. The site contains up-to-date
information on The Binding Site’s products, and may therefore contain information on
medical devices and other products or uses of those products that are not approved or
cleared in other countries or regions.
This site is not intended to promote off label use of any of The Binding Site’s
products. To obtain appropriate product information for your country of residence,
please contact your local distributor.

View source:

Bradwell et al. [81] measured κ and λ concentrations in early morning urine samples from 66 normal individuals using Freelite immunoassays (Figure 6.5 and Table 6.3). When compared to sFLC data from the same study, the range of urine FLC concentrations was much wider than for serum, and κ/λ urine FLC ratios were more variable. Presumably, this reflects differences in renal handling, urine dilution and mucosal secretion of FLCs between individuals.

A wide range of normal urine FLC concentrations was similarly observed by Snyder et al., who established a 95% reference range for the urine Freelite ratio of 1 - 19 using 91 healthy adult donors [166]. The authors attributed the relatively poor diagnostic sensitivity of the urine FLC assay (80%) to the wide reference ranges and a high background of polyclonal FLC in the urine. It is important to note that international guidelines do not recommend the use of urinary FLC immunoassays [167]. Arguments in favour of serum over urine FLC assays are further discussed in Chapter 24.

Questions

Answers

Because the smaller monomeric κ molecules are cleared faster by the kidneys and enter the urine more readily than dimeric λ molecules (Section 6.1).

Because FLC removal in renal impairment becomes dependent upon the reticuloendothelial system which removes κ and λ FLC at the same rate. Serum levels begin to reflect production rates and κ concentrations therefore increase relative to λ (Section 6.3 and Chapter 3).